1. Field of the Invention
The present invention relates to an image display apparatus capable of correcting a picture defect of a human figure or the like, and more particularly to an image display apparatus in which when an aspect ratio of a screen is different from an aspect ratio of an input image signal, even in the case where an input image is displayed without changing the aspect ratio of the input image signal, a picture defect of a human figure or the like can be automatically corrected.
2. Description of the Related Art
When an image of an input image signal is displayed on a display means having an aspect ratio different from an aspect ratio of the image, in the case where the image is displayed while the aspect ratio of the input image signal is kept, the following image modes are conceivable.
FIG. 14A shows a state in which a display means has an aspect ratio of (4:3) and an input image signal of (16:9) is displayed on this, and in this case, non-screen portions are formed at the upper and lower portions of the screen. FIG. 14B shows a case where an amount of horizontal over scan is increased to eliminate the non-screen portions. Besides, as shown in FIG. 14C, when the image is nonlinearly distorted, all the image can be displayed without a defect.
Similarly, in the case where an image of an input image signal having an aspect ratio of (4:3) is displayed on a screen having an aspect ratio of (16:9), it is possible to conceive a mode in which non-screen portions are attached to the right and left portions as shown in FIG. 14D, a mode in which an amount of vertical over scan is increased as shown in FIG. 14E, or a mode in which the image is nonlinearly distorted and is displayed as shown in FIG. 14F.
Incidentally, such image display processing can be realized by changing the phase or inclination of a deflection signal.
Now, as described above, when the aspect ratio of a screen is different from the aspect ratio of an input image, a part of the image must be sacrificed, a surplus image (non-screen portion) having no influence on the image must be inserted, or the image must be distorted.
Accordingly, it is apparent that the method of attaching the non-screen portions as in FIG. 14A or 14D can not effectively use the display screen. In the method of increasing the amount of over scan as in FIG. 14B or 14E, a picture defect is increased, so that there is a case where lack of information to be displayed occurs.
When the display mode in which the picture defect occurs is adopted, although an image display position for a screen can be adjusted by a user himself, since the display position is fixed after the adjustment, the display position must be always adjusted for every image content in order to prevent the picture defect, which is very inconvenient. In the case of FIG. 14C or 14F in which a nonlinear processing such as a wide zoom processing is performed, although the picture defect is decreased, there is a problem that its circularity can not be held.
Further, since the position where the picture defect occurs is indefinite, there may be a case that information important for the user is defective.